
<?php
/**
 * User: lie
 * Date: 2020/12/7 16:17
 * Title: 字符串与 HTML 标记相互转换
 * Error:
 * Description:
 */
// 定界符<<< 声明时不能有空格
$str=<<<mark
<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>字符串与 HTML 标记相互转换</title>
</head>
<body>
    <form action="" method="post">
    用户名：<input type="text" name="username">
    <br>
    密码：<input type="password" name="password">
    <input type="submit" name="sub" value="登录">
</form>
</body>
</html>
mark;
echo $str;
